The invention relates to an apparatus for adjusting a headrest on a backrest of a vehicle seat in which the headrest is supported on a rocker that is pivotal round a pivot axis fixed on the backrest frame.
An apparatus of this type is known from U.S. Pat. No. 5,795,019. With the known apparatus, the headrest is pivoted forward in the case of a rear impact on the vehicle. This is due to inertial forces acting on the rocker owing to the inert mass of the vehicle occupant""s body and pivot forwards the rocker and the headrest supported thereon.
With the present invention, an adjusting device, of which the adjusting movement can be transmitted to the rocker via a movement-transmitting device, in particular a Bowden cable, is provided on the vehicle seat. The adjusting device preferably has a self-locking design so that the headrest is held in the respectively adjusted position. The adjusting device is preferably supported on the backrest frame. The adjusting movement is preferably transmitted to the rocker by a Bowden cable. For this purpose, the Bowden cable sheath can act as a movement-transmitting element while the Bowden cable wire is fixed on the backrest frame. For example, a worm gear that is self-locking can displace a sleeve connected rigidly to the end of the Bowden cable sheath with an internal worm thread for achieving the adjusting movement by means of an electrical or manual drive. This movement is transmitted to the rocker by the Bowden cable sheath that is stiff in its axial direction. The headrest can therefore be brought into any desired position, in particular into a comfortable position during normal travel. In the respectively adjusted position, the headrest and the rocker are supported on the backrest frame via the movement-transmitting element, in particular the Bowden cable sheath, which is designed rigidly in the movement-transmitting direction. Two Bowden cables that are supported on the backrest frame on the two sides of the backrest can optionally be used for transmitting the adjusting movement. At its top, the backrest frame can have a frame part which bridges the two lateral frame parts of the backrest frame and on which the upper end of the respective Bowden cable wire is fastened. Guide orifices for supporting rods on which the headrest is fastened can also be provided on this substantially horizontally extending frame part.